Control structure of grinding machine

ABSTRACT

A grinding machine includes a sensor for detecting the variation of the current of a motor thereof to determine the timing that a grinding assembly thereof touches a workpiece. An automated control system computes the grinding path of the grinding assembly according to the timing. Thus, all of the workpieces are cut the same even though the workpieces are held at different positions on the chuck.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a machine tool, and more particularly to a control structure of a grinding machine.

2. Description of the Related Art

As the level of modern industrial machining is heightened, a variety of automated digital machine tools become more and more popular and important. Among them, the internal diameter grinding machine is one of the most popular ones. There are numerous similar grinding machines in the present market, but most of them have to change their cutters before grinding an internal diameter of a workpiece (e.g. bearing). The machine has to be stopped in the replacement step of the cutters to reduce the efficiency of production. As a result, there is still much space for improvement of the grinding machine.

FIG. 1 shows a conventional grinding machine, which includes a machine base 11, on which a chuck 12, a grinding assembly 13, and an automated control system 14 are provided. The chuck 12 is provided for holding a workpiece 15. The grinding assembly 13 is driven by a motor 16 and controlled by the automated control system 14 to grind the workpiece 15 in a predetermined distance. However, such grinding machine has drawbacks as recited hereunder:

1. While the grinding machine grinds a plurality of the workpieces 15, the automated control system 14 sets the same grinding path of the grinding assembly 13 every time for each workpiece 15. However, there are tolerances among the workpieces 15. Even if the grinding paths of the grinding assembly 13 are same, but the workpieces are not grinded the same. Therefore, the workpieces are grinded defectively, especially for the precise workpieces.

2. After the workpiece 15 is grinded by the grinding assembly 13, the grinded workpiece 15 has to be manually replaced for a new one. While the original workpiece 15 is unfixed from the chuck 12, the new workpiece 15 is not held at the same position, such that the new workpiece 15 is not grinded the same to be defective.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a control structure of a grinding machine, which includes an automated control system having a control wire, a grinding assembly, a motor provided for driving/controlling the grinding assembly, and sensor mounted on the control wire. While the grinding assembly touches a workpiece, the sensor generates a signal and transmits it to the automated control system, and then the automated control system computes the grinding path of the grinding assembly to enable the same grinding path for each workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a conventional grinding machine;

FIG. 2 is an elevational view of a first preferred embodiment of the present invention;

FIG. 3 and FIG. 4 show the feed controller of the first preferred embodiment of the present invention in operation, and

FIG. 5 is an elevational view of a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 2, an internal diameter grinding machine of the first preferred embodiment of the present invention includes a machine base 2, a chuck 3, a grinding assembly 4, a motor 5, a sensor 6 and an automated control system 7.

The machine base 2 is provided for mounting the above elements thereon.

The chuck 3 is mounted on the machine base 2 for holding a workpiece 31.

The grinding assembly 4 is mounted on the machine base 2 to be controlled by the automated control system 7 for movement along a predetermined path, having a work portion 41 corresponding to the chuck 3.

The motor 5 is mounted on the machine base 2 for driving the grinding assembly 4 to move.

The sensor 6, which is an amperemeter in this embodiment, is electrically connected to the motor 5 via a control wire 61 for monitoring the current of the motor 5. While detecting a variation of the current, the sensor 6 generates a signal and transmits it to the automated control system 7.

The automated control system 7 is mounted on the machine base 2. The sensor 6 is electrically connected to the automated control system 7 via a control wire 71. The automated control system 7 is provided for setting a distance of the movement of the grinding assembly 4. The automated control system 7 computes a grinding path of the grinding assembly 4 when receiving the signal from the sensor 6.

As shown in FIGS. 3 and 4, while the workpiece 31 is held on the chuck 3, and then setting the automated control system 7 and the motor 5 drive the grinding assembly 4 to move along a predetermined path. When the work portion 41 of the grinding assembly 4 touches the workpiece 31, a resistance is generated between the workpiece 31 and the grinding assembly 4 to increase the load of the motor 5 to further variate the current of the motor 5. Meanwhile, the sensor 6 detects the variation of the current to generate the signal and transmit it to the automated control system 7. When receiving the signal, the automated control system 7 computes the grinding path of the grinding assembly 4 to enable the same grinding path for each workpiece 31 held on the chuck 3 even though the workpieces 31 are held at different positions on the chuck 3, thus enhancing the processing precision of the workpiece 31.

FIG. 5 shows an end surface grinding machine 8, on which a sensor 6 is provided to detect the variation of the current of the motor 5. Same as above, when the work portion 41 of the grinding assembly 4 touches the workpiece 31, a resistance is generated between the workpiece 31 and the grinding assembly 4 to variate the current of the motor 5. The sensor 6 generates a signal and transmits it to the automated control system 7 when detecting the variation of the current of the motor 5, and then the automated control system 7 computes the grinding path of the grinding assembly 4 when receiving the signal.

In conclusion, the present invention provides the sensor for detecting the variation of the current of the motor to determine the timing that the grinding assembly touches the workpiece. The automated control system computes the grinding path of the grinding assembly according to the timing. Thus, the present invention enables all of the workpieces to be cut the same even though the workpieces are held at different positions on the chuck. 

1. A grinding machine comprising: a machine base; a chuck provided on said machine base for holding a workpiece; a grinding assembly controllably movably mounted on said machine base for corresponding to said chuck; a motor mounted on said machine base and electrically connected with said grinding assembly via a control wire for driving said grinding assembly to move on said machine base; an automated control system mounted on said machine base and electrically connected with said motor via a control wire for setting a path of said grinding assembly; and a sensor mounted on said control wire between said motor and said automated control system for monitoring a current of said motor; wherein said sensor detects a variation of said current of said motor when said grinding assembly touches said workpiece, said sensor generates a signal and transmits it to said automated control system, and then said automated control system computes a grinding path of said grinding assembly.
 2. The grinding machine as defined in claim 1, wherein said sensor is an amperemeter. 